Lactobacillus is one of the major bacteria present in an intestinal tract of animals including human. Due to advantageous effects on in vivo physiological activity of an animal, the Lactobacillus has been variously added to diverse probiotic products.
Meanwhile, monosodium L-glutamate (MSG) that is used to food additives and chemical seasonings for taste and flavor has been used worldwide since it was found from kelp extract by Dr. Ikeda in 1907 and developed as a product by Ajinomoto Co., Japan.
Natural foods containing relatively large amount of glutamic acid, which is a major material of the MSG are breast milk, weed, kelp, mushroom, meats, tomato, parmesan cheese, beans and the like, and when it is taken in the form of natural food, there is no example reported side effects or pathological symptoms.
However, after Chinese-American physician Kwok confirmed that some people taken excessive MSG showed various symptoms such as headache, weakness, rigidity and chest pain in 1968, controversy over harmful effect of the MSG was started for the first time. Then, in 1981, the New England Journal of Medicine reported that two asthma patients experienced asthma attack 12 hours after eating at Chinese restaurant (Baker G J et al. 1981), and reported that intake of excessive amount of MSG causes brain cell damage and endocrine system disruption, and in particular, it is harmful to infants, and also it causes eyes and brain damages after infant mice take commercially available MSG-added infant food (Olney J W, Sharpe L G 1969). Further, it was confirmed that after orally administrating 0.5 g/Kg body weight of MSG into young mice (10˜12 days-old), 52% of the tested mice showed neuronal cell damage at a rate of 100% every 1 g administration (Lowe C U et al. 1970). The term ‘MSG Symptom Complex (MSC)’ was started being used in that the MSG is not a problem of only Chinese restaurant. Also, when taking 2.5 g or more of MSG, symptoms such as headache, muscle stress, muscle numbness, weakness, facial flushing and the like was shown in the double blind, placebo controlled study (placebo, 1.25, 2.5, 5 g MSG) of Yang W H et al. (1997), and the symptom study after taking MSG of Schaumburg et al. (1969) reported that symptoms of the MSG Symptom Complex are insensibility or numbness, headache, migraine, palpitation, chest tightness, weakness, aching, facial flushing, cold sweating, lacrimation, syncope, dizziness, shudder attacks, paresthesias, arrhythmias, tachycardia. Besides that, it was reported that excess MSG intake causes or aggravates asthma, atopic dermatitis, respiratory arrhythmia, nervous disease, indigestion and the like (Allen D H et al, 1987), Federation of American Societies in Experimental Biology (FASWB) reported through a report in 1995 that some sensitive people may show allergy reaction as the MSG Symptom Complex, and in some serious intractable asthma patients, asthma may worsen after taking the MSG in an amount of about 0.5 to 2.5 g per day (Geha et al. 2000).
However, despite these harmful effects of the MSG, the MSG is used as a taste enhancer for cooking at home and restaurant, and as an additive for food processing production; and it is known that in advanced countries, average daily intake of MSG per person is 0.3 to 1.0 g (Geha R S et al. 2000), and in Korea, the MSG intake is the highest as 1.977 g among the currently known countries (Jeong, Youngsub, Asiatoday, 2013). It is expected that it may be difficult to reduce MSG consumption in the future due to eating out culture and growing trend of instant food consumption of busy modern people.